ESTRADIOL AND MALE-FEMALE ASSOCIATION PATTERNS IN WILD SPIDER MONKEYS

Spider monkeys (Ateles sp.) exhibit convergent behavior and association patterns with chimpanzees (Pan troglodytes). Despite these similarities, they differ in their sexual signals. Female chimpanzees exhibit conspicuous sexual swellings, whereas female spider monkeys conceal ovulation. Given this difference, it is unclear if female reproductive state influences male-female associations in spider monkeys as documented in chimpanzees. Here, I present preliminary results investigating the relationships between male association and estradiol in female spider monkeys. Behavioral data (mean=14.72 hours/individual) and fecal hormone data (mean=11.27 samples/individual) were collected over 15 months on 11 females at El Zota Biological Field Station, Costa Rica. Females spent a mean of 16.5% of time in association with males, but individual rates varied from 3% to 50% of total focal observations. There was a positive correlation between male association rate and mean estradiol concentrations (Spearman’s rs=0.589, N=11, p=0.028). Whinny rates were previously found to correlate with estradiol concentrations (rs=0.818, p=0.002). I suggest that estradiol concentration may modulate vocal cues, and potentially chemical cues, to attract mates. However, further research is needed to examine temporal variation in these patterns. This research was funded with the assistance of the Wenner-Gren Foundation, the American Philosophical Society, and The Ohio State Graduate Alumni Grant and Sigma Xi.